heat treating question

[redneckshootist]

whats the best way to heat treat an ak flat reciver after it is bent?

[FEDUPWBS]

http://www.akfiles.com/forums/showthread.php?t=14475

MAPP torch is the safest bet. Lots of info here. Also great links. Pm me w/ questions.

[redneckshootist]

thanks fedupwbs, there was a link at that site that led me to this

http://pookieweb.dyndns.org:61129/AK/docs/construction/heattreat.htm

it gives a step by step mapp gas heat treatment

[FEDUPWBS]

Dont forget to do the ejector outside the gun! OOPS!

[vandal]

What would be the harm of doing it once it is welded in, if you annealed any extra area you accidentally heat treated?

Dont forget to do the ejector outside the gun! OOPS!

[FEDUPWBS]

Takes lots of gas cause the receiver acts as a heat sink. but not the end of the world

[hawk81]

You will need to get it to about Rockwell 40 c. I hope you have a hardness checker.

[M. Sage]

What kind of steel are these made of that they aren't already about 40C? That's not terribly hard.

[jumbopanda]

What kind of steel are these made of that they aren't already about 40C? That's not terribly hard.

No steel has a hardness of 40C in it's annealed state. 4140 steel is roughly 23 Rockwell C if you don't heat treat it.



If you want to try something a little bit more advanced (although not THAT advanced), check this out:

http://www.akfiles.com/forums/showthread.php?t=25310

http://www.akfiles.com/forums/showthread.php?t=25780

I'd also like to add that in my most recent attempt I used a proper quenching oil and got ZERO warping.


But for most people a simple spot heat treating with a MAPP torch is enough.

http://www.gunsgutsandgod.com/section%20three.htm

Be sure to not that the steel will not glow blue or purple or any of those colors. It simply forms an oxide layer on the surface and you should see a thin ring of it appear as you are heating it. I would recommend removing the heat source every few seconds to check the color. Be sure not to heat the thing too much when tempering and make it too soft. I would rather have it a little bit too hard than too soft.

[M. Sage]

It's been a while since I took a class on that stuff. IIRC, there are some steels that you can heat treat without a quench.

I do remember that the trick to quenching a heat-treat piece without warping it is to dunk that sucker fast. And I remember not to let any part of your body over the container (we used a bucket). Splash-back can really hurt you.

[hawk81]

Some metals require thermal quench and some require liquid quench. The chemistry of the metal dictates the type of heat treatment necessary to achieve the required hardness and toughness of the material.

[FEDUPWBS]

Jumbo jst gotcha on that one for my sigline buddy!

[jumbopanda]

Jumbo jst gotcha on that one for my sigline buddy!

[ar15barrels]

IIRC, there are some steels that you can heat treat without a quench.

Those would be the "A" series steels (A for air hardening).
There are also "O" series steels. (Yep, you guessed it, O is for oil hardening.)
Then there are some "W" series steels. Guess what you quench them in...

There are a whole bunch of different steels designed for specific things.
You have to really know your steels before you figure out how to harden and temper them.

[JPglee1]

For regular mild steel, or what you'd find in an AK flat, I usually heat it up to a dull cherry red glow, then quench it in USED motor oil...

The carbon in the used motor oil can actually help to surface harden the steel and it can also turn it a darker color (which I like)

I have also used warm salt water as a quench.... When you DO quench it, be sure to have a large volume of liquid, as it WILL heat it up, and also be sure to move it around as you're quenching it. if you leave it in one spot, especially with water, it can cause problems with your hardening.

Its kinda hard to explain without showing someone... one of those "gotta see it" things to truly explain the ins and outs.


J